That he is a troubled man is obvious.
In less formal English, the fact plus a that-clause is often used as a subject instead of a simple that-clause.
The fact that what they are doing is dangerous is not important here.
The fact that your boss is offering to do your job for you worries me.
The normal way of commenting on a fact is to use an impersonal it structure. See paragraph 8.122.
8.125 People also use the fact plus a that-clause as the object of prepositions and of verbs that cannot be followed by a simple that-clause.
He is proud of the fact that all his children went to university.
We missed the fact that the children were struggling to understand the exercise.
nominal use of wh-clauses
8.126 When you want to talk about something that is not certain or definite, or about which a choice has to be made, you can use clauses beginning with a wh-word or whether, like the clauses used for reported questions. They can be used after prepositions, and as the subject of verbs such as be, depend, and matter.
…the question of who should be President.
The teacher is uncertain about what she wants students to do.
What you get depends on how badly you were injured.
Whether I went twice or not doesn’t matter.
Whether you think they are good or not is not important.
8.127 Structures consisting of a wh-word plus a to-infinitive, which refer to a possible course of action, are used after prepositions but not usually as subjects.
…the problem of what to tell the adopted child.
…a book on how to avoid having a heart attack.
People are worried about how to fill their increased leisure time.
8.128 Note that if-clauses, which are used for reported questions, cannot be used after prepositions or as the subject of a verb.
Non-finite clauses
8.129 A non-finite clause is a subordinate clause that contains a participle or an infinitive, and that does not contain a stated subject.
There are two types of non-finite clause. One type begins with a subordinating conjunction.
She fainted while giving evidence in court.
You’ve got to do something in depth in order to understand it.
This type of clause is dealt with in the sections on adverbial clauses (paragraphs 8.6 to 8.82).
The other type of non-finite clause does not begin with a subordinating conjunction.
He pranced about, feeling very important indeed.
I wanted to talk to her.
This type of clause sometimes consists of a participle and nothing else.
Ellen shook her head, smiling.
Rosie, grumbling, had gone to her piano lesson.
Clauses that contain a participle and do not begin with a subordinating conjunction are explained in the following paragraphs.
types of non-finite clause
8.130 The non-finite clauses discussed in this section work in a similar way to relative clauses, and, like relative clauses, they may be used for distinguishing a noun from others or they may simply add extra information.
Some clauses simply add extra information. These are called non-defining clauses. They are dealt with in paragraphs 8.132 to 8.143. These clauses are often used in writing, but are not usually used in spoken English.
Others are used to distinguish a noun from all other possibilities. These are called defining clauses. They are dealt with in paragraphs 8.144 and 8.145. These clauses are occasionally used in both written and spoken English.
position of non-defining clauses
8.131 Non-defining clauses can go in front of a main clause, after a main clause, or in the middle of one. A non-defining clause is usually separated by a comma from the words in front of it and after it.
Using non-defining clauses
8.132 Non-defining clauses give further information that is not needed to identify the person, thing, or group you are talking about.
The following paragraphs 8.133 to 8.138 explain how these clauses are used when they relate to the subject of the verb in a main clause. The subject is not mentioned in the non-defining clause.
-ing participle: events happening at the same time
8.133 If you want to say that someone is doing or experiencing two things at the same time, you mention one of them in the main clause and the other in a clause containing an -ing participle.
Laughing and shrieking, the crowd rushed under the nearest trees.
Jane watched, weeping, from the doorway.
Feeling a little foolish, Pluskat hung up.
Walking about, you notice something is different.
People stared at her. Seeing herself in a shop window, she could understand why.
Note that the -ing participle should always describe an action performed by the subject of the main part of the sentence. So, for example, you should not say Going to school, it started to rain. Instead, you should say Going to school, I noticed that it had started to rain.
-ing participle: one action after another
8.134 If you want to say that someone did one thing immediately after another, you mention the first action in a clause containing an -ing participle and the second one in the main clause.
Leaping out of bed, he dressed so quickly that he put his boots on the wrong feet.
-ing participle: reasons
8.135 If you want to explain why someone does something or why something happens, you say what happens in the main clause and give the reason in a clause containing an -ing participle.
At one point I decided to go and talk to Uncle Sam. Then I changed my mind, realising that he could do nothing to help.
The puppy would probably not live to grow up, being a tiny, weak little thing.
8.136 You can also use an -ing participle directly after a verb in a sentence such as I stood shivering at the roadside. This use is explained in paragraphs 3.189 to 3.201.